Freqrol-SF Series Overview:

The Mitsubishi Freqrol-SF or FR-SF units are offered in sizes ranging from 3.7kW to 45kW as the standard type drives. Other drive types offered besides standard would be high-speed, wide range constant output, small capacity, and positioning drives. The FR-SF series offers a range of new features that make it effective to use within a system compared to older units. Some features include Oriented spindle stop function, Accurate response to load, Accurate load meter, and high-speed tapping. FR-SF unit offers ease of use when it comes to parameters as they can be set by using switches on the unit itself, or on the numeric control display. Mitsubishi Freqrol-SF units have a 30% reduction of components making the unit more reliable compared to the past products.

Common Failures – Alarm Codes and Troubleshooting Steps

When it comes down to FR-SF series spindle drives, there are a couple of alarms that are more common than others. The two most common alarms are Over-Current (code 32) and Parameter Error (code 37). Both will be shown on the segment display. If the alarm was intermittent, the drive offers an alarm history where the last 3 alarm instances can be viewed.

Out of the two codes we mentioned above, code 32 – Inverter Over-Current – is by far the most common. One of the first checks that can be done once the alarm occurs is disconnecting the motor leads (U, V, W) from the drive and checking each output to the ground for any short in the circuit. If this test passes and there is no short between the leg and the ground it is safe to run the drive with the motor disconnected. If AL.32 appears with the motor disconnected there is an internal fault with the unit and will need to be sent in for repair. With over-current alarms, it is always recommended to meg test the motor and the cables to measure insulation to ensure there is no leakage to the ground. For the step-by-step instruction on how to meg a motor, check out this video guide on our YouTube channel:

How to check spindle motor and cables on your machine.

Along with Alarm 32, Parameter Error (Alarm 37) is the next most frequent alarm. This happens when either parameter is out of range or when linked to control there is a discrepancy between what’s on the unit and what is on the control. With FR-SF units you can press the “mode” button on the unit until you see “rd off” displayed, then click on “up” or “down” buttons until you see “P.E.##” (stands for parameter error).

The unit is telling you which parameter is causing the issue so you may change or match to manufacture specification. If you cannot set a parameter, it is possible you are NC bus-linked and need to change through control parameters. If none of these methods work, and you are still getting the parameter error along with the “0” as data for parameter this means the data is corrupted and there’s an internal fault with the unit, which may need to be sent for repair.

If you see “—” on the display, either a parameter is not being set or there is a communication issue with the control that causes the error. Communication issues between the control and the unit will cause “parameter” alarms. All settings and parameters need to be re-checked – even a single incorrect setting can cause a corruption of the data.

At Precision Zone, we guide our clients toward the best decisions that serve their business needs. If you have specific repair or replacement questions, get in touch with our expert customer support team at 800-551-4420 or

Written by:

Marketing & Creative Director at IcarTeam, and supporting afiliated businesses,
including Precision Zone, Precision Education Integrators and Alfra Tools.
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